Substitution.
Here is an example.
Let x be equal to 3 and y equal to 3.

From this we can conclude that the values of both x and y are equal to three therefore x and y have the same value and are equal.

Here in your case we have:

Hope this helps.
r3t40
Answer:
(a) 0.4242
(b) 0.0707
Step-by-step explanation:
The total number of ways of selecting 8 herbs from 12 is

(a) If 2 herbs are selected, then there are 8 - 2 = 6 herbs to be selected from 12 - 8 = 10. The number of ways of the selection is then

Note that this is the number of ways that both are included. We would have multiplied by 2! if any of them were to be included.
The probability = 
(b) If 5 herbs are selected, then there are 8 - 5 = 3 herbs to be selected from 12 - 5 = 7. The number of ways of the selection is then

This is the number of ways that both are included. We would have multiplied by 5! if any of them were to be included. In that case, our probability will exceed 1; this implies that certainly, at least, one of them is included.
The probability = 
Answer:
the awnser would be 2
Step-by-step explantion
u have 1 apple and get 1 from a friend and that adds up to 2